Maternal pro-inflammatory status in obesity regulates placental function

描述(由申请人提供)：超过60%的美国女性进入怀孕阶段，超重或肥胖，胎儿过度生长在这些怀孕中很常见。胎儿过长增加了创伤性出生损伤的风险，并使婴儿在童年和以后的生活中容易患上肥胖症、糖尿病和高血压。超重/肥胖妇女胎儿生长增加的机制在很大程度上是未知的。我们的总体模型是，超重/肥胖女性体内促炎细胞因子、瘦素和游离脂肪酸(FFA)水平的增加会导致胎盘释放出更多的TNF-和IL-6。我们认为，这些细胞因子刺激氨基酸转运体的表达和活性，在体内将导致增加对胎儿的营养输送，并最终促进胎儿生长。为了解决这一模型，我们的中心假设是，FFA通过多种信号通路刺激胎盘氨基酸的转运，包括与Toll样受体4结合，激活MAPK和NF，促进细胞因子的产生，如IL-6。我们进一步认为，滋养层细胞产生的细胞因子在母体血浆中循环，通过影响部分由STAT3介导的特定氨基酸转运体的转录、翻译和/或膜转运，上调滋养层细胞的氨基酸转运。我们将在三个具体目标中阐述这一中心假说：1.确定母亲高体重指数(BMI)对关键细胞内信号通路和胎盘营养物质转运能力的影响。我们将招募75名瘦、超重和肥胖的孕妇，并测量胎盘中关键的细胞内信号通路和营养转运体的表达和活性，并将其与母亲的BMI和代谢参数相关联。2.建立FFA对胎盘细胞因子产生的影响，明确细胞内信号转导途径。利用原代人滋养层细胞和siRNA技术，我们将描绘细胞内信号通路，将FFA与增加细胞因子释放联系起来。3.确定促炎症细胞因子对胎盘氨基酸转运的影响，并确定相关的细胞内信号转导机制。我们将利用siRNA方法研究细胞内关键信号分子如STAT3在培养的人原代滋养层细胞中的作用，并将检测胎盘氨基酸运输能力的三个潜在调节水平：基因转录、蛋白质翻译和膜运输。我们的初步数据有力地支持了我们的中心假设。这项拟议的研究具有创新性，因为他们有望确定肥胖引起的母亲代谢紊乱与胎盘功能变化之间的机制联系，胎盘功能变化增加了对胎儿的营养供应。这项研究的意义在于，它将为胎儿过度生长的机制提供新的信息，这可能有助于开发新的干预策略，以减少胎儿过度生长及其短期和长期健康后果。 公共卫生相关性：超重和肥胖的妇女通常会生下大婴儿，这些婴儿在儿童时期就有很高的患肥胖症、糖尿病和高血压的风险。我们认为胎盘营养物质转运的改变是母体肥胖导致出生体重增加的重要机制。这与公共卫生高度相关，因为这一新信息可能会导致新的干预策略来缓解胎儿过度生长，这可能会减少下一代肥胖和糖尿病的流行。

DESCRIPTION (provided by applicant): More than 60% of American women enter pregnancy overweight or obese and fetal overgrowth is common in these pregnancies. Fetal overgrowth increases the risk for traumatic birth injuries and predisposes the baby for development of obesity, diabetes and hypertension in childhood and later in life. The mechanisms underlying the increased fetal growth in overweight/obese women are largely unknown. Our overall model is that increased levels of pro-inflammatory cytokines, leptin and free fatty acids (FFA) in overweight/obese women cause an increase in TNF- and IL-6 release from the placenta. We propose that these cytokines stimulate amino acid transporter expression and activity, which in vivo will result in increased nutrient delivery to the fetus and ultimately increased fetal growth. To address this model our central hypothesis is that FFA stimulate placental amino acid transport mediated by multiple signaling pathways including binding to Toll Like Receptor 4 resulting in activation of MAP kinase and NF which promotes production of cytokines such as IL-6. We further propose that cytokines, produced by the trophoblast and circulating in maternal plasma, up-regulate trophoblast amino acid transport by affecting transcription, translation and/or membrane trafficking of specific amino acid transporter isoforms, mediated in part by STAT3. We will address this central hypothesis in three specific aims: 1. Determine the impact of high maternal body mass index (BMI) on key intracellular signaling pathways and placental nutrient transport capacity. We will recruit 75 lean, overweight and obese pregnant women and measure expression and activity of key intracellular signaling pathways and nutrient transporters in placenta and correlate these to maternal BMI and metabolic parameters. 2. Establish the effect of FFA on placental cytokine production and define the intracellular signaling pathway mediating the effects. Using primary human trophoblast cells and siRNA techniques, we will delineate the intracellular signaling pathway linking FFA to increased cytokine release. 3. Determine the effect of pro-inflammatory cytokines on placental amino acid transport and identify the intracellular signaling mechanisms involved. The role of key intracellular signaling molecules, such as STAT 3, will be investigated employing siRNA approaches in cultured human primary trophoblast cells, and we will examine three levels of potential regulation of placental amino acid transport capacity: gene transcription, protein translation and membrane trafficking. Our preliminary data give strong support for our central hypothesis. The proposed studies are innovative because they are expected to identify a mechanistic link between the perturbed maternal metabolism in obesity and alterations in placental function, which increases nutrient delivery to the fetus. The significance of this study is that it will provide novel information on the mechanisms underlying fetal overgrowth, which may allow for the development of new intervention strategies in order to reduce fetal overgrowth and its' short- and long-term health consequences. PUBLIC HEALTH RELEVANCE: Overweight and obese women often deliver large babies, which have a high risk to develop obesity, diabetes and hypertension already in childhood. We propose that changes in placental nutrient transport constitutes an important mechanism by which maternal obesity leads to increased birth weight. This is highly relevant to public health since this new information may lead to novel intervention strategies to alleviate fetal overgrowth, which could lessen the epidemic of obesity and diabetes in the next generation.